// the pavilion

moneysport

a play-money prediction parlor. the chips are points — nothing to buy, nothing to cash out, nothing to lose. it keeps a small vig on every race, and you can watch that edge drain a purse the way real ones do.

purse
1,000±0
stake

pick a runner to back.

the ledger

races
0
hit rate
—
total staked
0
the vig's share
−0
this book sums to 0%. a fair one sums to 100. the surplus is the house's, and because it is spread evenly across the field, every runner carries the same expected return: -10.7% — identical to within a third of a point, which is only the rounding of the displayed odds. the favourite and the longshot are priced to lose you the same fraction. there is no runner on this card that beats the vig, which is why the purse line bends the way it does given enough races.

// what this is, and isn't

The chips are points. There is nothing to buy, no way to add funds, no way to cash out, and no account — close the tab and the purse is gone. It is a scale model, built to make one mechanic visible: the overround. The race result is sampled from each runner's true probability, so the racing is honest; what is not honest is the pricing, which is shortened by 12% and takes its cut whether you win or lose.

This is the pavilion from Money, the Sport with No Referee. That note argues that making money shares sport's structure — irreducible, un-shortcuttable, played in real time and scored — while lacking sport's two saving graces: symmetric rules and contained stakes. Here both graces are restored. The stakes are points, the rules are printed on the card, and there is a reset button. Watching a purse drain under a stated edge with nothing at risk is the cheapest possible way to learn what the same curve costs when the graces are missing.

Honest limits: real books move their prices as money arrives, carry different margins per runner, and are not this tidy. Variance here is real, so a short session can easily end up ahead — that is exactly the thing that makes the edge hard to see from the inside, and it is why the ledger reports the vig's cumulative share separately from your result.